It's simulation, plus the elementary school solution of the univariate linear equation

Actually, many of the duplicates can be used with functions, but I always like to copy and paste!(x)

Improvement of P1022 Calculator

Topic Background

NCLNCL is a lab specializing in the improvement and upgrade of calculators. Recently, the lab received a task entrusted by a company: the ability to solve one-variable first-order equations needs to be added to the calculator of a certain model of the company.The lab delegated the task to a new beginner, Mr. ZL.

Title Description

In order to accomplish this task well, Mr. ZLZL first studied some examples of univariate linear equations:

4+3x=84+3x=8

6a-5+1=2-2a6a−5+1=2−2a

-5+12y=0−5+12y=0

Mr. ZLZL was informed by his supervisor that only three mathematical symbols, integer, lowercase letters and +, -, =, were included in a unary one-time equation typed on the computer (of course, the symbol'-'can be used as either a minus sign or a minus sign).There are no parentheses or division signs in the equation, and the letters in the equation represent unknown numbers.

You can assume that another programmer is making a judgement of the correctness of the equations you type, or that the one-time equations you type are valid and have a unique real solution.

Input and Output Formats

An equation of one degree with one variable.

The result of solving the equation (exactly three decimal places).

Input and Output Samples

6a-5+1=2-2a

a=0.750

#include <iostream>
#include <cmath>
#include <stdio.h>
#include <cstring>
using namespace std;
int main()
{
	char a[110]={0};
	
	cin>>a;
	
	double s=0,g=0;//Result, constant before unknown number

	int i;
	
	char y;

 	for(i=0;i<strlen(a);){
 		
 		if(a[i]=='=') break;
 		
 		if(a[i]=='+'||i==0&&a[0]!='-'){
 			
 			if(i!=0) i++;
 			
 			int t=0;
 			
 			while(a[i]>='0'&&a[i]<='9'){
 				
 				t=t*10+(a[i]-'0');
 				
 				i++;
			 }
			 
			 if(a[i]>='a'&&a[i]<='z'){
			 	
			 	y=a[i];
			 	
			 	if(t==0) t=1;
			 	
			 	g+=t;
			 	
			 	i++;
			 }else{
			 	
			 	s-=t;
			 	
			 }
 			
		 }
		 
		 if(a[i]=='-'){
		 	
		 	i++;
 			
 			int t=0;
 			
 			while(a[i]>='0'&&a[i]<='9'){
 				
 				t=t*10+(a[i]-'0');
 				
 				i++;
			 }
			 
			 if(a[i]>='a'&&a[i]<='z'){
			 	
			 	 	y=a[i];
			 	
			 	if(t==0) t=-1;
			 	
			 	g-=t;
			 	
			 	i++;
			 	
			 }else{
			 	
			 	s+=t;
			 }
		 	
		 	
		 	
		 }
 		
 		
	 }
	 
	 int h=++i;
	 
	 for(;i<strlen(a);i++){
	 	
	 	
	 		if(a[i]=='+'||i==h&&a[h]!='-'){
	 			
	 		if(i!=h) i++;
 			
 			int t=0;
 			
 			while(a[i]>='0'&&a[i]<='9'){
 				
 				t=t*10+(a[i]-'0');
 				
 				i++;
			 }
			 
			 if(a[i]>='a'&&a[i]<='z'){
			 	
			 	 	y=a[i];
			 	
			 	if(t==0) t=1;
			 	
			 	g-=t;
			 	
			 }else{
			 	
			 	s+=t;
			 	
			 }
 			
		 }
		 
		 if(a[i]=='-'){
		 	
		 	i++;
 			
 			int t=0;
 			
 			while(a[i]>='0'&&a[i]<='9'){
 				
 				t=t*10+(a[i]-'0');
 				
 				i++;
			 }
			 
			 if(a[i]>='a'&&a[i]<='z'){
			 	
			 	 	y=a[i];
			 	
			 	if(t==0) t=-1;
			 	
			 	g+=t;
			 	
			 }else{
			 	
			 	s-=t;
			 }
		 	
		 	
		 	
		 }
	 	
	 	
	 }
	 
	 double x=s/g;
	 
	 //cout<<s<<" "<<g<<endl;
	 
	 printf("%c=%.3f\n",y,x);
	 
	 
	 return 0;
}